Nice to see a DC01 still in use!
Right, remove the clear bin, then press the yellow semi-circular button behind it to remove the hose away from the vacuum (with the wand removed). Now try sliding the hose entirely into the wand, does the metal end of the wand stick out the bottom? Are there any dents at the bottom of the wand?
Also, when you said you took the vacuum(s) apart, did you remove the wand release catch? Maybe it's not in securely and thus causing the wand to slide in a few millimetres away from the grooves in the wand to the plastic fins on the main body for the wand to slide into.
Also, (some DC01's have this) but let's assume your DC01 is yellow/grey, so when you remove the hose away from the vacuum, look down into the hose where the hose sits. There should be a yellow or blue (Depending on your Dc01 colour) plastic thing sticking out, these are supposed to be spring loaded and I've seen a few with this broken, maybe the wand is catching on that? I'm not sure how much you took the vacuum apart either sorry.
Any questions please ask